畸形波作用下考虑水弹性上浪砰击效应的船舶运动响应研究

With giant wave heights and strongly destructive effects, freak waves have caused ship overturning and structure fracture many times. Due to the fact that the formation of freak waves is complicated and strongly nonlinear and that severe green water and impact effects usually occur, the mechanism of freak-wave-ship interaction is much different from that of the common wave-ship interaction. The study of freak-wave-ship interaction is by now not highly-developed yet, and existing research work usually lacks full consideration of the hydroelastic green water and impact phenomenon. Therefore, a fast ship-motion evaluating method, which takes into account the nonlinear effects of freak waves as well as the green water and impact phenomenon, is required. This project considers the high-energy features and green water effects of freak waves, and develops 3-D freak-wave simulation methods as well as the FSI method which processes complex transient hydroelastic impact issues. The project studies the influence of various factors during the green water and impact events, and proposes a theoretical model of the freak-wave-induced deck overtopping. Considering the wave nonlinearity and green water effects, the conventional ship motion equation is modified, and a fast prediction method of ship motion under freak waves is finally established. The proposed method can be used during ship design and safety assessment.

畸形波是一种具有大波高的强破坏性波浪，其多次造成船舶的结构破坏与倾覆。畸形波形成机理复杂，具有强非线性，常常导致剧烈甲板上浪砰击，因而其对船舶作用的机理规律与常规波浪存在较大差异。目前畸形波对船舶作用的相关研究尚不成熟，现有研究往往对复杂的水弹性上浪砰击现象考虑不足，目前工业界急需一种可以考虑畸形波强非线性及上浪砰击效应的船舶运动响应快速评估办法。本课题针对畸形波的高能量特性以及复杂水弹性上浪砰击过程，研究建立畸形波三维数值模拟方法和瞬态复杂自由液面流固耦合算法。研究畸形波水弹性上浪砰击过程中多种因素的影响，建立畸形波水弹性上浪砰击理论预报模型。考虑畸形波强非线性及上浪砰击效应，对经典的船舶运动学方程进行合理修正并求解。最终形成一套较快速有效的船舶在畸形波作用下运动响应计算分析办法，为船舶设计及安全性评估提供参考。

畸形波是一种具有大波高的强破坏性波浪，其多次造成船舶的结构破坏与倾覆。畸形波形成机理复杂，具有强非线性，常常导致剧烈甲板上浪砰击，因而其对船舶作用的机理规律与常规波浪存在较大差异。目前畸形波对船舶作用的相关研究尚不成熟，现有研究往往对复杂的水弹性上浪砰击现象考虑不足，目前工业界急需一种可以考虑畸形波强非线性及上浪砰击效应的船舶运动响应快速评估办法。本项目针对畸形波的高能量特性以及复杂水弹性上浪砰击过程，建立了畸形波三维数值造波方法和可以有效吸收畸形波高能量/质量的守恒消波法，提出了一套具有良好收敛性和稳定性的适合模拟瞬态上浪砰击效应的整体隐式流固耦合算法。在数值水槽中模拟了畸形波及其甲板上浪砰击现象，明确了畸形波水弹性上浪砰击过程中多种因素的影响，建立了畸形波水弹性上浪砰击理论预报模型。考虑畸形波强非线性及上浪砰击效应，对经典的船舶运动响应间接时域法进行修正，提出了一套较快速有效的船舶在畸形波作用下运动响应时域计算分析方法。计算结果表明该运动响应计算方法能够达到一定的预报精度，可以在船舶设计阶段快速计算畸形波作用下的船体运动响应，评估畸形波甲板上浪过程，为结构设计和船体安全性评估提供参考。